Itchy bumps thought to be Pityriasis Rosea but its not. What is it?

[Ber70]

I have a rash that started all over my stomach but has spread to my breast, chest, shoulders, sides, underarms and my back.  It continues to spread & the dermatologist does not know what it is.  My biopsy results came back as negative for Pityriasis Rosea. I am currently using a prescribed anti-itch cream (I think it's spelled Kenalog or Keno???) & Xyzal but nothing is stopping the itching.  What is it?  I have seen the doctor twice now & this thing will not stop itching & the doctor does not know what it is.  I have stopped exercising, I have not changed the products that I used but I want this thing to go away.  I have had this problem for about 5 weeks now.  Any suggestions?

[Dr_Aparna]

Hi,
This could be an allergic reaction to some food item or medication that you have started in the recent past.
When an irritant comes into contact with your body, your immune system sends chemicals, including histamine, to fight it. The sudden spike in histamine levels can cause an outbreak of hives/rashes in the upper layers of the skin.

Some of the common trigger factors are foods like eggs, shellfish, nuts, berries, Drugs (any drug can touch off an allergic reaction, although allergies to penicillin, sulfa, and aspirin are especially common). These are the two most common reasons for a widespread reaction like yours. Pollens and plants (nettles, poison ivy, poison oak, and so on) as well as Insect bites or stings could also be responsible for this rash.

You can take anti-histamine medications for the rash. The extent of the rash will affect the time taken for it to heal.
Continue this medication for a week to ten days. You can also apply a mild Corticosteroid ointment to alleviate the rash. This is recommended only for a short period of time.

[t74]

I took had a sudden onset of rashes on my arms and breast AFTER I scratched them.  For weeks they itched.  First said to be pityrias, then some fungal thing, then an allergy test showed I was supposedely allergic to every thing food, trees, etc.  things I've been consuming all my life.  almost 6 mos later, after stopping my  exercising, doing and elimination diet to see if i had true food allergies, i still itch (mostly on my breasts).  this is not fun.  you may want to see if you are allergic to anything.  Maybe you tried some diff. foods or teas??  My prob today is I want to know WHY At 34 all of a sudden I'm allergic??? good luck.